I will answer your first question from my own experience as someone who earned a PhD in Biomedical Sciences from a top-level research medical school in the United States, and spent much of his long academic career on the faculty of health sciences at a major research university. (Others may have had different opinions based on their own experiences.)
My research has led me to believe that the health sciences has more
job opportunities/flexibility, less competition, and higher
compensation for a given position when compared to the life sciences.
This is absolutely true. Basically, it comes down to money available for research. In academia, this money comes primarily from government funding. The NIH, which funds health sciences, has MUCH more funding to distribute, and in larger amounts, than the NSF, which funds biological sciences in general. And of course, there is big pharma and other health care industries having plentiful funds for research and development.
Health sciences professors, who are almost always on the faculties of schools of medicine and other health sciences, are more highly paid than biology-related professors, who usually are on the faculties of schools of liberal arts and sciences.
And yet, perhaps surprisingly, health science positions, though rigorous in their requirements, are generally less competitive (i.e., less applicants per position opening) than in life sciences. This is because fewer PhDs have the clinical/biomedical/health backgrounds that health sciences schools are looking for.
